Nobody Knows

Keiko and her four children move into a cramped Tokyo apartment, with only Akira known to the landlord. The younger siblings Shigeru and Yuki are smuggled inside in suitcases, while Kyōko arrives separately by train. Keiko keeps the children isolated from the outside world, and Akira is the only one allowed to go outside.

Keiko tells Akira that she has a new boyfriend and plans to get married, promising the children will lead normal lives afterward. Akira looks doubtful about the promise and wonders how they will survive. The family remains largely hidden from the outside world as the situation becomes more precarious.

Keiko leaves home and is away for months, leaving only a small amount of money for the children. Akira takes charge of paying rent and caring for his siblings, while he visits various men who might be Yuki's father to beg for money. The family frays at the edges as money and stability shrink.

Keiko returns with gifts for the children, momentarily brightening their lives, but she soon leaves again. She promises to be back in time for Christmas, but omits the return and the family is left waiting. The cycle of hope and abandonment deepens the kids' dependence on one another.

Keiko marries and disappears permanently, leaving Akira and Kyōko to assume surrogate parental roles. The seasons pass without her return, from New Year into spring, and the siblings grow more capable yet more isolated. Akira struggles to fill both caretaker and provider roles for all the children.

The rent becomes unaffordable and the family subsists on cheap food from the convenience store. Akira secretly investigates potential fathers for Yuki in a bid to raise funds, trying to shield the others from hardship. The apartment degenerates as care and cleanliness slip away.

On Yuki's birthday, she asks to go outside to wait for their mother at the train station. The siblings share a day out together while Keiko does not return. Akira promises Yuki that someday he will take her on the Tokyo Monorail to see airplanes at Haneda Airport.

Akira befriends two boys near his own age at a game arcade who begin visiting the family apartment to play and roughhouse. His attention drifts away from his younger siblings as distractions mount. The apartment grows more neglected and the children suffer from the lack of regular care.

Several months later the two boys have entered junior high. Akira goes to their school and invites them over to play, but they refuse, and he overhears them comment that his house smells like garbage. He tries to salvage the situation by taking the siblings to a nearby park and buying them candy.

In an effort to repair trust, Akira brings his siblings to a nearby park to play and buys them candy and toys. They start a garden on the veranda by planting seeds from wildflowers inside instant noodle cups, finding small joys amid deprivation. The family bonds through these simple acts.

Electricity, gas, and water are finally turned off, forcing the children to wash at the park's facilities. Shigeru befriends Saki, a high school girl who starts visiting and helping with chores. When Saki offers Akira money obtained through enjo kosai, he rejects the help and distances himself to protect the siblings.

With summer approaching, Akira plays in a junior high baseball match after being spotted by a team coach. While he is away, Yuki dies after falling from a stool. The loss devastates the family and tests their fragile resilience.

After Yuki's death, Akira accepts Saki's financial support and they buy boxes of Yuki's favorite chocolates. They place the chocolates with Yuki in a suitcase and transport it to a field near Haneda Airport. They dig a grave, bury the suitcase, and return to the apartment, where the remaining siblings continue their life together.

The film ends with Akira, Kyōko, Shigeru, and Saki walking home together, a fragile but enduring bond formed in the face of hardship. Saki's hair is in pigtails, echoing Yuki's past, symbolizing hope and continuity for the children. They move forward, carrying memories and a sense of responsibility for one another.